This is my second car with this body style (the first being a 2001 M Coupe), and even though it is genuinely tiny with a tight passenger compartment, I was always comfortable in the previous M Coupe. No so in this Z3 Coupe - my head was rubbing on the roof! It didn't take long to figure out that the driver's seat was stuck in the highest position. Pressing the button to lower it made motor noises, but no movement. Drat.
After following instructions in the Bentley manual to disconnect the battery to keep the airbags from blowing, I removed the seat. I had to break out my biggest pull handle - the seat bolts had been seriously torqued down, probably to try to cure the slight rocking motion the seats have. That's a common problem in Z3s, and the fix is some custom deldrin bushings. Jack has them in stock.
Maybe you haven't seen this view before - it's a power seat from underneath:
The motor (letter A) turns, and drives the gearbox (the shiny thing under the bracket at B), which rotates the screw and therefore moves the bracket (letter C). It's attached by a pin (below letter D) to the mechanism that raises and lowers the seat.
Here's a closer view with the same letters - as the screw turns, it should disappear into the bracket. Since the gearbox can''t move, the bracket does, pulling the lift mechanism along with it.
The problem was the everything was bound up, and the screw wouldn't turn. First order of business: find the bind. I removed the pin at letter D, and then used a hammer to tap on the seat lift mechanism. It moved, so no bind there.
Then, I removed the motor, since I already knew it was trying to turn. That brought up a refrain that will probably become familiar in this project: Somebody's Been Here Before! One of the four screws holding the motor was gone. Those screws had T20 Torx heads. Fortunately, a couple of years ago, my good friend Dave gave me the mother of all fancy bit sets, and it had just what I needed:
Once the motor was unhooked, I rotated the bracket, and two things were immediately clear:
1. The screw was jammed in the bracket.
2. The gearbox was damaged - it would rotate most of a turn, and then jam. Probably, the jammed screw led to the gearbox damage.
Twisting with a pair of channel lock pliers popped the screw free, and then it would rotate freely in the bracket. Note in the picture below how it is jammed tight to the bracket at the bottom.
Once the bracket was free, I spun it down the screw almost all the way, to lower the seat. Since the gearbox is still jammed, I wanted to lower the seat for now manually. You can see how the screw is now down into the bracket:
I put it all back together (a fussy job, getting that motor shaft back in place) and put the seat back in the car. Relief! Two or three inches of headroom now, and a better relationship to the pedals, steering wheel and gauges.
One more pic: while the seat was out, I took a picture of the explosive seatbelt pre-tensioner that is causing the SRS (airbag) light to stay lit. Both seats will have to come back out to replace those at some point. I guess the canister is where the propellant lives. The manual has dire warnings against trying to explode them yourself - they are supposed to be returned to the manufacturer for disposal.
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